The present invention relates to a sealing device for the passage of a cable between two volumes that are at different pressures, especially for the penetration of a submarine cable into a volume at a pressure less than the pressure of the surrounding water.
At the present time there are various systems for providing the sealed penetration of a submarine cable subjected to dynamic forces into a volume at a pressure less than the pressure of the surrounding water, for example in a submerged machine, a cabinet or any other volume.
The over-molding system, with or without bonding, which is not suitable for high pressures, is relatively bulky, requires special tooling, is relatively tricky to implement, cannot be dismantled without destroying it and, in the variant with bonding, cannot be used for all cable jacket materials.
The gland (called stuffing box) system, consisting in axially compressing several annular packing elements made of elastomer in a box for the purpose of gripping these elements radially inward against the cable jacket and outward against the box is likewise limited in pressure and is effective only in the short term, but does have the advantage of being able to be dismantled, of being more compact, of being not very expensive and of being able to be used for all cable jacket materials.
The so-called cuff system, comprising a cuff mounted on a metal insert, is suitable even for very high pressures, can be used for all cable jacket materials and is very effective over time, but is bulky, requires special tooling, is difficult to implement and cannot be dismantled.
The so-called equipressure system, which makes use of a volume of liquid maintained under pressure, is a system which is complex, bulky and difficult to implement.
The subject of the present invention is a cable sealing device, especially for the penetration of a submarine cable into a volume at a pressure less than the pressure of the surrounding water, this device making it possible, by very simple means, to remedy most of the difficulties and problems encountered with the known sealing systems mentioned above.
The sealing device forming the subject of the invention, for the passage of a cable between two volumes at different pressures, especially for the penetration of a submarine cable into a volume at a pressure less than the pressure of the surrounding water, comprises a gland with at least one packing element in the form of an annular body made of elastomer, compressed axially in a box for the purpose of it being clamped radially inward against the cable jacket and outward against the box. The annular element of the packing element closest to the high-pressure volume is extended, along its inside diameter, toward said volume by a sleeve which, in the manner of a cuff, surrounds and grips the cable jacket from the inside of the box of the gland right into the high-pressure volume.
This packing element with an integrated cuff combines the advantages of the gland system with the advantages of the cuff system, remedying at the same time most of the drawbacks of each of these two systems. The device is particularly simple, easy to implement, compact and able to withstand high pressure differences. Because of its compactness, it allows a particular cable which is fitted with it to be wound on the drum. No bonding of the cable jacket is necessary, as is the case for the usual cuff system. The device can therefore be dismantled without any problem and can be used in any cable jacket material whatsoever.
The sleeve forming the cuff has advantageously, at least at its free end, in the relaxed state, an inside diameter less than the outside diameter of the cable jacket.
Preferably, the sleeve forming the cuff has a length greater than its diameter, advantageously a length greater than the outside diameter of the annular body of the packing element of which it forms part, and preferably a length at least equal to twice this diameter.
The thickness of the sleeve forming the cuff is small compared with the radial thickness of the annular body of the packing element of which it forms part. The thickness of the sleeve is advantageously less than ⅕ of the thickness of said annular body and preferably less than {fraction (1/10)} of the inside diameter of this annular body.
The sleeve may advantageously have the form of a truncated cone converging from the annular body toward its free end.
Advantageously, the sleeve may have an outside rim at its free end.
An illustrative and nonlimiting embodiment of a sealing device according to the invention will be described below in greater detail, with reference to the appended schematic drawings; in these drawings: